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Patent 2778238 Summary

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(12) Patent Application: (11) CA 2778238
(54) English Title: METHOD FOR MANUFACTURING A DEVICE FOR REGENERATING BIOLOGICAL TISSUES, PARTICULARLY FOR REGENERATING TISSUES OF THE CENTRAL NERVOUS SYSTEM
(54) French Title: PROCEDE DE FABRICATION D'UN DISPOSITIF CONCU POUR REGENERER DES TISSUS BIOLOGIQUES, EN PARTICULIER DES TISSUS DU SYSTEME NERVEUX CENTRALEM
Status: Dead
Bibliographic Data
(51) International Patent Classification (IPC):
  • A61L 27/24 (2006.01)
(72) Inventors :
  • SANNINO, ALESSANDRO (Italy)
  • MORTINI, PIETRO (Italy)
(73) Owners :
  • AS & PARTNERS S.R.L. (Not Available)
(71) Applicants :
  • AS & PARTNERS S.R.L. (Italy)
(74) Agent: FASKEN MARTINEAU DUMOULIN LLP
(74) Associate agent:
(45) Issued:
(86) PCT Filing Date: 2010-10-07
(87) Open to Public Inspection: 2011-04-28
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/EP2010/065048
(87) International Publication Number: WO2011/047970
(85) National Entry: 2012-04-19

(30) Application Priority Data:
Application No. Country/Territory Date
MI2009A001804 Italy 2009-10-20

Abstracts

English Abstract

A method (100) for manufacturing a device (1) for regenerating biological tissues, particularly for regenerating tissues of the central nervous system, and a device (1) that can be manufactured with said method (100), the device (1) comprising an outer sheath (2) based on collagen which is substantially tubular and can be interposed between the endings of a biological tissue to be regenerated, and at least one supporting element (3) based on collagen, which is accommodated inside the outer sheath (2).


French Abstract

L'invention concerne un procédé (100) de fabrication d'un dispositif (1) conçu pour régénérer des tissus biologiques, en particulier les tissus du système nerveux central, et un dispositif (1) que l'on peut fabriquer par ce procédé (100). Ledit dispositif (1) comprend une gaine externe (2) à base de collagène qui est sensiblement tubulaire et que l'on peut placer entre les extrémités d'un tissu biologique à régénérer, et au moins un élément de soutien (3) à base de collagène, situé à l'intérieur de la gaine externe (2).

Claims

Note: Claims are shown in the official language in which they were submitted.





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CLAIMS

1. A method (100) for manufacturing a device (1) for regenerating
biological tissues, particularly for regenerating tissues of the central
nervous
system, characterized in that it comprises the steps of:

- injecting (9) an aqueous suspension of collagen in a mold (11) that
has a cavity (22) with a substantially elongated shape along a predefined
direction (21),
- immersing (12) said mold (11), containing said aqueous suspension
of collagen, in a bath of liquid nitrogen along said preferred direction (21),

for freezing said aqueous suspension of collagen,
- sublimating (14) said aqueous suspension of collagen contained in
said mold (11),
- extracting (15) from said mold the supporting element (3) for
regenerating biological tissues as obtained at the end of said sublimation
step,
- drying (16) said supporting element (3).


2. The manufacturing method according to claim 1, characterized in
that said inner cavity (22) has a transverse cross-section that is
substantially
shaped like a semielliptical lobe.


3. The manufacturing method according to one or more of the
preceding claims, characterized in that said immersion step (9) comprises a
control of the rate of immersion of said mold (11) in said liquid nitrogen
bath so as to generate a thermal gradient substantially along said preset
direction (21) and form ice crystals within said aqueous suspension of
collagen.

4. The manufacturing method according to one or more of the
preceding claims, characterized in that during said immersion step (9) said
rate of immersion of said mold (11) containing said aqueous suspension of
collagen in said liquid nitrogen bath is preferably equal to 0.1 mm/s.


5. The manufacturing method according to one or more of the




18


preceding claims, characterized in that it comprises a step of pre-
sublimation (13) of said collagen suspension contained in said mold (11) in
a freeze-dryer at a preset temperature, preferably equal to -40 °C, and
for a
preset time, preferably equal to 1 hour, said pre-sublimation step (13) being
performed between said immersion step (12) and said sublimation step (14).


6. The manufacturing method according to one or more of the
preceding claims, characterized in that said sublimation step (14) comprises:
- lowering the inside pressure of a freeze-dryer containing said
aqueous solution to a preset value, preferably equal to 200 mTorr, while
keeping said temperature preferably equal to -40°C,
- raising the inside temperature of said freeze-dryer to a preset value,
preferably equal to 0 °C,
- holding said inside temperature for a preset time, preferably equal
to 17 hours,
- raising the inside temperature of said freeze-dryer to a preset value,
preferably equal to 20 °C,
- injecting air into said freeze-dryer and restoring the atmospheric
pressure inside said freeze-dryer.

7. The manufacturing method according to one or more of the
preceding claims, characterized in that it comprises a step (17) for
stabilizing said supporting element (3) to reduce the degradation rate of said

supporting element (3) in vivo by means of a cross-linking treatment, said
stabilization step (17) being performed after said drying step (16).


8. The manufacturing method according to one or more of the
preceding claims, characterized in that it comprises a step of sterilization
(18) with dry heat of said supporting element (3).

9. The manufacturing method according to one or more of the
preceding claims, characterized in that it comprises a step (103) for
inserting
at least one said supporting element (3) in an outer sheath (2) based on
biocompatible material and having a substantially tubular shape, in order to




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obtain a device (1) for regenerating biological tissues which can be
interposed between the ends to be regenerated.


10. The manufacturing method according to one or more of claims 1
to 8, characterized in that it comprises a step (103) for inserting two
supporting elements (3) in an outer sheath (2) based on biocompatible
material and having a substantially tubular shape in order to obtain a device
(1) for regenerating biological tissues of the spinal cord, which can be
interposed between the endings to be regenerated.


11. A supporting element (3) for regenerating biological tissues,
particularly for regenerating tissues of the central nervous system, which
can be obtained from a manufacturing method (102) according to one or
more of the preceding claims.

12. The supporting element (3) according to claim 11, characterized
in that it has an elongated shape along a preferred axis (30) with a
substantially semielliptical transverse cross-section.

13. The supporting element (3) according to one or more of claims 11
and 12, characterized in that it has a controlled structural porosity, with
the
pores oriented substantially longitudinally with respect to its preferred axis

(30), so as to allow the biological tissue to grow inside said pores.


14. The supporting element (3) according to one or more of claims 11
to 13, characterized in that it is based on collagen with additions of at
least
one of fibronectin, hyaluronic acid, elastin and fibrin.

15. A device (1) for regenerating biological tissues, particularly for
regenerating tissues of the central nervous system, obtainable by means of a
manufacturing method according to one or more of claims 1 to 10.


16. The regeneration device (1) according to claim 15, characterized
in that it comprises at least one supporting element (3), according to one or
more of the preceding claims 11 to 14, accommodated inside an outer sheath
(2) based on collagen and having a substantially tubular shape.

17. The regeneration device (1) according to claim 15, characterized


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in that it comprises two supporting elements (3) according to one or more of
claims 11 to 14, which are accommodated within an outer sheath (2) based
on collagen and having a substantially tubular shape and are substantially
mutually parallel along the longitudinal axis (29) of said outer sheath (2).

18. The regeneration device according to claim 16 or 17,
characterized in that said outer sheath (2) has a structural porosity in which

the pores are oriented substantially radially with respect to its longitudinal

axis (29) so as to allow the growth of the biological tissue within said
pores.

Description

Note: Descriptions are shown in the official language in which they were submitted.



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METHOD FOR MANUFACTURING A DEVICE FOR REGENERATING
BIOLOGICAL TISSUES, PARTICULARLY FOR REGENERATING
TISSUES OF THE CENTRAL NERVOUS SYSTEM

Technical field
The present invention relates to a method for manufacturing a device
for regenerating biological tissues, particularly for regenerating tissues of
the central nervous system, and to a device that can be manufactured with
such method.

Background art
Currently, in the medical field, regenerative medicine is becoming
established as a therapeutic method for treating several types of lesions. In
this modern approach, closing of the wound is achieved by means of the
synthesis of scar tissue; particularly in induced regeneration, a bioactive
structure is arranged in the wound, modifying the original healing and repair
mechanism and inducing regeneration of physiological tissue.

The regeneration devices used, known in the technical jargon as
"scaffold", have an essential role in this process because they act both as
physical supports and as guides for tissue growth and supply adapted
stimuli, acting as insoluble regulators of cellular function.

Scaffolds, with appropriate composition, structural, mechanical and
degradation characteristics, allow therefore a regenerative healing process to
take place.
In particular, the manufacturing of scaffolds with pores oriented along
a specific direction are used in the tublation technique, which consists in
the
use of a tubular structure to reconnect damaged tissue endings.
The characteristics of the pores of the scaffold, which generally
influence the success of the scaffolds as regenerative guides, comprise the
void fraction (the percentage of porosity), pore diameter distribution and
pore interconnectivity.
For applications related to the peripheral nervous system, it has been


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observed that the orientation of the pores of the scaffold plays a critical
role
in its performance. Studies concerning the peripheral nervous system, but
also the central nervous system, have demonstrated that structures oriented
along an axis have a strong regenerative activity.

In fact, scaffolds made of collagen in which the pores are aligned
along an axis are known and are used both for lesions of the peripheral
nervous system and for lesions of the central nervous system such as, for
example, spinal cord lesions.
In particular, porous scaffolds of the known type are obtained by slow
immersion of a suspension of biocompatible material, such as collagen and
glycosaminoglycans, in a freezing bath and by subsequent freeze-drying.

It has been verified that the immersion rate and the temperature of the
freezing bath affect significantly the dimensions of the pores and their
orientation in the matrix.
Experimental tests have shown that for cylindrical scaffolds with a
diameter from 1.5 millimeters to 3.8 millimeters, only particular
combinations of immersion rate and freezing temperature lead to axially
oriented pores.
For example, US Patent application 2008/0102438 discloses a method
for manufacturing tubular scaffolds based on collagen that have a gradient
of porosity and of pore size that lies in a radial direction, a pore
distribution
that is oriented radially and an outer surface that is permeable to proteins
and impermeable to cells. In the method described in the above-mentioned
patent, a suspension of collagen is introduced in a mold until such mold is
filled. The mold is spun about its own axis so as to cause the sedimentation
of the suspension and create a hollow tubular structure in its interior.

For creating the porosity inside the hollow tubular structure, a portion
of the components that constitute the suspension are first immobilized and
then removed.
In particular, in the case of a water-based collagen suspension, in


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order to immobilize and subsequently remove the components, one uses first
the immersion in liquid nitrogen and then lyophilization, known in the
technical jargon as "freeze-drying".
With this method, tubular scaffolds of collagen are obtained with a
gradient in the porosity and size of the pores in a radial direction, a pore
distribution oriented in a radial direction, and an outer surface that is
permeable to proteins and not to cells.

This method allows simple and precise control of the geometry and
porosity of the tubular structure.
However, scaffolds of the background art, used for example in
peripheral nerve regeneration, are constituted by a tubular body with a
single direction of orientation of the porosity, which is not sufficient to
ensure correct regeneration in the case of lesions that affect, for example,
the spinal cord.
In the case of applications concerning the regeneration of the spinal
cord, in fact, the scaffold, besides providing a connection between the two
severed endings, must be also capable of reproducing the particular
architecture of the spinal cord, which is characterized by an outer portion of
white matter and two internal lobes of gray matter.
Despite the fact that the presence of a connection between the two
severed endings is sufficient to induce regeneration of the damaged tissue, it
has been noted that the micro structural, mechanical and composition
characteristics of the tubular structure proper and of the material inserted
in
the cavity of the tubular structure influence significantly the quality of the
regeneration.

Disclosure of the invention
The aim of the present invention is to provide a device for
regenerating biological tissues and the respective manufacturing method,
particularly for regenerating tissues of the central nervous system such as,
for example, the spinal cord.


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Within this aim, an object of the invention is to provide a
regeneration device capable of protecting the site of the implant from the
infiltration of external tissue, while remaining permeable to cells from the
inside outward, and at the same time having on its inside such a structure as
to facilitate axonal regrowth of the right and left lobes of lesioned marrow,
by providing the axons with adequate physical and chemotactic support.
Another object of the invention is to provide a regeneration device
that is highly reliable, relatively easy to provide and which has competitive
costs.
This aim and these and other objects that will become better apparent
hereinafter are achieved by a device for regenerating biological tissues and
by the respective manufacturing method, characterized in that it comprises,
particularly for the provision of the inner portion of the scaffold, the steps
of:
- injecting an aqueous suspension of collagen in a mold that defines a
cavity having an elongated shape,
- immersing said mold, containing said aqueous suspension of
collagen, in a bath of liquid nitrogen along its longitudinal axis for
freezing
said aqueous suspension of collagen,
- sublimating said aqueous suspension of collagen contained in said
mold, for example in a freeze-dryer,
- extracting from said mold the supporting element for regenerating
biological tissues as obtained at the end of said sublimation step,

- drying, for example in a dryer, said supporting element.
Brief description of the drawings
Further characteristics and advantages of the invention will become
better apparent from the description of a preferred but not exclusive
embodiment of a device for regenerating biological tissues and of the
respective manufacturing method, according to the invention, illustrated by
way of non-limiting example in the accompanying drawings, wherein:


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Figure 1 is a perspective view of a supporting element according to
the invention;
Figure 2 is a perspective view of the outer sheath of a regeneration
device according to the invention;
5 Figure 3 is a perspective view of a regeneration device according to
the invention, constituted by an outer sheath and by two supporting
elements;
Figure 4 is a flowchart of the method of manufacturing the
regeneration device according to the invention;

Figure 5 is a flowchart of the step of manufacturing the supporting
element according to the invention;

Figure 6 is a perspective view of a mold used to provide the
supporting element according to the invention;

Figure 7 is a perspective view of a support for molds used to
manufacture supporting elements according to the invention.

Ways of carrying out the invention
With reference to Figures 1 to 3, the regeneration device according to
the invention, generally designated by the reference numeral 1, comprises an
outer sheath 2 based on biocompatible material, preferably based on
collagen, which can be interposed between the two endings of biological
tissue to be regenerated.
More particularly, in a preferred configuration for applications aimed
at regeneration of the spinal cord the outer sheath 2 has a substantially
tubular shape.
The regeneration device 1 comprises at least one inner element 3
based on biocompatible material, preferably based on collagen,
accommodated inside the outer sheath 2 to facilitate biological regrowth of
the biological tissue.
Conveniently, for the application of regenerating the spinal cord,
there are two inner elements 3 that lie substantially parallel to each other


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and along a preferred axis 30, which is parallel to the longitudinal axis 29
of
the outer sheath 2, each one having a transverse cross-section shaped like a
semielliptical lobe.
For containing two supporting elements 3 and reproducing the outer
shape of the white matter of the spinal cord on which the regeneration
device 1 is to be implanted, the outer sheath 2 has, once it has been
implanted, a transverse cross-section with a substantially elliptical shape.

The two supporting elements 3 contained in it are thus arranged so as
to simulate the inner structure of the spinal cord, constituted by two lobes,
a
right one and a left one, of gray matter.
Advantageously, the outer sheath 2 has a porous structure, so that its
outer wall 4, having a higher relative density of collagen, has a reduced
average pore size so as to form a region that is permeable to proteins and
impermeable to cells.
Differently, the inner wall 5 of the outer sheath 2 can have a smaller
volumetric fraction of solid and, therefore, a lower relative density of
collagen, and a larger average pore size so as to constitute a region that is
permeable to the cells that are present inside the cavity 6 of the outer
sheath
2.
Conveniently, to allow a preferential cell migration from the cavity 6
of the outer sheath 2 toward the outer wall 4 through which inflow of cells
from the outside is however blocked, the pores of the inner wall 5 can be
oriented in a substantially radial direction with respect to the longitudinal
axis 29.
As already mentioned, each supporting element 3 has an elongated
shape along a preset direction with a transverse cross-section that is
substantially semielliptical and simulates the shape of the gray matter of the
corresponding lobe of the spinal cord.
As will be described in more detail, hereinafter, the supporting
element 3 has a relative density of collagen that is substantially constant in


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all directions.
Like the outer sheath 2, the supporting element 3 also has a porous
structure with controlled porosity.
In this case, however, the pores of the supporting element 3 are
oriented substantially longitudinally with respect to the longitudinal axis 29
of the outer sheath 2 to promote the regeneration of the biological tissue
inside said pores where the regeneration device 1 is applied.

In particular, for applications related to the spinal cord, said
longitudinal porosity is necessary in order to sustain the axial growth of the
axons and of the Schwann cells' channels of the spinal cord.
In a particularly advantageous configuration, the outer sheath 2,
directly after being manufactured and before its deformation necessary for
its implantation, has an outside diameter that is preferably equal to 12
millimeters and an inside diameter that is preferably equal to 10 millimeters.

In the same advantageous configuration, the semielliptical lobes of
the inner elements 3 have a major axis of the ellipse that is preferably equal
to 12 millimeters and a minor axis of the ellipse that is preferably equal to
6
millimeters.
Moreover, the pore size of the supporting elements 3, for example
comprised between 5 m and 20 m, is such as to promote axonal regrowth.
Advantageously, each one of the supporting elements 3, besides being
provided with a porous structure based on collagen, can comprise additions
of at least one among fibronectin, hyaluronic acid, elastin and fibrin.

With reference to the figures, the method 100 for manufacturing the
regeneration device 1, according to the invention, comprises a step 101 of
manufacturing the outer sheath 2 and a step 102 of manufacturing the inner
elements 3.
The manufacturing method 100, shown schematically in Figure 4,
comprises at least one step 103 of insertion of each supporting element 3
provided in the outer sheath 2.


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More precisely, the manufacturing step 101 can be performed by
means of a method known per se starting from an aqueous suspension of
Type I fibrillar collagen, which is derived, for example, from cattle hide,
and contains a high solid content, for example equal to 3% by weight.

This aqueous suspension is degassed by centrifugation, for example,
for 12 minutes at 6000 rpm for eliminating the air introduced during mixing.
The suspension is then stored at a temperature of about 4 C and,
before use, is left for a few hours at ambient temperature, comprised
between 18 C and 20 C, so as to reduce its viscosity and thus facilitate the
subsequent injection step.
In this way, the suspension is ready to be injected, for example by
means of a graduated pipette, into a tubular mold made, for example, of
PVC (polyvinyl chloride) or silicone.
Such tubular mold is subsequently sealed and inserted in a cylindrical
support which comprises a cylindrical body screwed to a base with one end.
The cylindrical support is made of copper or of a material with a similar
heat conductivity and is necessary for vertical coupling to a rotor.

Such rotor subjects the tubular mold and the aqueous suspension of
collagen contained therein to a rotation, about a specific axis of rotation,
at a
preset rate and for a preset time so as to cause a phenomenon of
sedimentation of the collagen on the walls of the mold, thus producing the
desired inner geometry of the structure of the outer sheath 2.

For obtaining an outer sheath 2 that runs along the longitudinal axis
29, the latter is made to coincide with the rotation axis of the mold. In
particular, by adjustment of the rotation rate of the rotor the inside
diameter
of the outer sheath 2 is adjusted.
The fact that the collagen is in an aqueous suspension and, therefore,
the fact of having components of sufficiently different density, allows
complete removal of the collagen from the portion that surrounds the
rotation axis of the mold, thus providing a hollow tubular structure.


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More precisely, the tubular mold, which contains the aqueous
suspension of collagen, is immersed, while still under rotation, in a bath of
liquid nitrogen and frozen for a preset time, at the end of which the mold is
extracted from said bath and rotation is stopped.

This freezing makes it possible to create ice crystals inside the
sedimented collagen structure which are subsequently removed by
sublimation and drying, thus providing the desired porous structure.

As regards the supporting element 3, it is obtained from the
manufacturing step 103, which comprises the steps illustrated in the
flowchart of Figure 5.
More precisely, the manufacturing step 103 comprises a step 8 in
which the preparation of the aqueous suspension of Type I fibrillar collagen
occurs, which collagen is derived, for example, from cattle hide and
contains a high solid content, for example equal to 3% by weight, from
which suspension the desired supporting element 3 is to be obtained.

Subsequently, one moves on to step 9, in which this suspension is
injected into a mold 11 made, for example, of PVC (polyvinyl chloride) or
silicone.
With reference to Figure 6, advantageously the mold 11 is constituted
by a body 20 whose shape is substantially elongated along a predefined
direction 21 and defines an inner cavity 22 having a transverse cross-section
that is substantially shaped like a semielliptical lobe, which corresponds to
the geometrical shape that the supporting element 3 shall have.

More precisely, said body 20 has a single opening 23, arranged at one
of its ends, through which the injection of the aqueous suspension of
collagen is performed.
The mold 11 further comprises a closing element 24, which can be
coupled to the opening 23 to form a closed inner volume.
For allowing an easier grip of the mold 11, on the opposite side with
respect to the opening 23 the base of the mold 11 has a protruding outer rim


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The mold 11 is then immersed over its whole length, which is
preferably equal to 35 millimeters, in a container that contains liquid
nitrogen at a very slow rate, for example, 0.1 mm/s, following a direction
5 which is parallel to its main direction 21.
This immersion allows the development, along the longitudinal axis
30 of the supporting element 3, of a distinct thermal gradient associated
with the transport of heat. Therefore the crystals, which are formed by
solidification of the aqueous solution of collagen, have a shape which is
10 elongated in the direction of heat transport, that coincides with the
direction
of immersion.
In order to treat simultaneously a plurality of molds and thus optimize
the productivity of the manufacturing step 103, an adapted support 3 for a
plurality of molds 11 is used.
With reference to Figure 7, the support 3, which allows the
simultaneous immersion of a plurality of molds 11 in a container of liquid
nitrogen, has a cage-like structure shaped substantially like a
parallelepiped,
on the upper face 26 of which a matrix of cavities 27 is formed adapted to
accommodate the molds 11.
The cavities 27, which are also formed on the lower face 28 of the
support 3, have such a geometric shape as to allow the insertion of the
molds 11 and their retention in the correct position in order to avoid
accidental movements on the plane at right angles to the direction of
insertion.
The immersion step occurs preferably with rate control, so as to allow
the desired development of a thermal gradient substantially along said preset
direction and to form ice crystals inside the aqueous suspension of collagen.
This speed control consists substantially in controlling the rate of immersion
of the mold 11 in the bath of liquid nitrogen.
For this purpose, the rate control is aimed at maintaining an


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immersion rate that is substantially constant and preferably equal to 0.1
mm/s.
Once the mold 11 has been extracted from the bath of liquid nitrogen,
after a time sufficient to achieve the freezing of the aqueous suspension of
collagen along the whole length of the mold 11, said mold is introduced in a
freeze-dryer, in which the pre-sublimation step 13 occurs.

In this step, the mold 11 is kept at a preset temperature, preferably
equal to -40 C, for a preset time equal to 1 hour.

Subsequently, still inside the freeze-dryer, the sublimation step 14
occurs in which first the internal pressure of the freeze-dryer is lowered to
a
preset value, preferably equal to 200 mTorr, while the temperature is
preferably kept equal to -40 C, and then, once said value of the pressure has
been reached, the internal temperature of the freeze-dryer is raised to a
preset value, preferably equal to 0 C.

The mold 11 is kept at such temperature for a preset time, preferably
equal to 17 hours, and then the inside temperature of the freeze-dryer is
raised to a preset value preferably equal to 20 C, for melting the previously
obtained crystals.
Subsequently, once air has been injected into the freeze-dryer to
restore atmospheric pressure inside it, the mold 11 is extracted from the
freeze-dryer.
During the subsequent extraction step 15, the supporting element 3,
thus obtained at the end of the sublimation step 14, is removed from said
mold 11.
Finally, in step 16, the supporting element 3 is placed in a dryer to be
dried.
Steps 14 and 16 are used to remove the aqueous component frozen
during the immersion step 12, to obtain the desired porous structure of the
supporting element 3.
Preferably, the supporting element 3 thus obtained can undergo a


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stabilization step 17 with the aim of reducing the degradation rate when
implanted.
This stabilization step 17 occurs by means of a cross-linking
treatment, which acts on the density of the cross-linking bonds that exist
among the macromolecules of collagen.

More particularly, one of the procedures used can be
DeHydroThermal Cross-Linking (DHT), which is a physical cross-linking
treatment that does not provide for the use of cross-linking agents and, in
particular, is performed in a vacuum oven for a period of time that varies
from 24 to 48 hours at a temperature preferably equal to 121 C with a
pressure preferably equal to 100 mTorr. Other cross-linking procedures can
include the use of carbodiimide, formaldehyde vapors, alone or together
with DHT.
Finally, advantageously, the supporting element 3 undergoes a dry
heat sterilization step 18, which makes it possible to avoid damaging and
degrading the structural integrity of the supporting element 3. This dry heat
sterilization treatment (Dry-Heat Sterilization, DHS) is preferably
performed in a vacuum oven under standard conditions, i.e., for a period of
time preferably equal to 2 hours and at a temperature preferably equal to
160 C.
The outer sheath 2, whose manufacture can comprise steps similar to
the stabilization step 17 and sterilization step 18, and the supporting
element
3 are provided by means of two independent processes and only when
implantation occurs they are assembled together by insertion of at least one
supporting element 3 in the outer sheath 2.
As already mentioned, the assembly and insertion operation 103 can
entail a deformation of the outer sheath 2.
Since the structure of the spinal cord must be simulated, during the
insertion step 103 two supporting elements 3 are inserted in the outer sheath
2 with the function of promoting the axonal regrowth of the right and left


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lobes of the lesioned spinal cord by providing the axons with an adequate
physical and chemotactic support.
In practice it has been found that the device according to the
invention fully achieves the intended aim, since the regeneration device
makes it possible to facilitate biological regrowth of biological tissue.

In particular, in applications for regeneration of the spinal cord, the
regeneration device, by having two supporting elements 3 that run
substantially parallel to each other along the longitudinal axis of the outer
sheath and each of which has a transverse cross-section shaped like a
semielliptical lobe, is capable of simulating the inner architecture of the
spinal cord constituted by two lobes, right and left, of gray matter.
Moreover, the fact that the outer sheath has, once implanted, a
substantially oval transverse cross-section allows it to contain two
supporting elements and, above all, to reproduce the outer shape of the
white matter of the spinal cord on which the regeneration device is to be
implanted.
Moreover, the fact that the outer wall of the outer sheath has a higher
relative density of collagen and a reduced average pore size makes it a
region that is permeable to proteins and impermeable to cells.

The fact is also not negligible that the inner wall of the outer sheath,
by having a lower relative density of collagen and a larger average pore
size, makes it possible to constitute a region that is permeable to the cells
that are present inside the cavity of the outer sheath.
Moreover, the fact that the pores of the inner wall are oriented in a
substantially radial direction with respect to the longitudinal axis of the
outer sheath allows a preferential cell migration from the cavity of the outer
sheath toward the outer wall, through which the entry of cells from the
outside is however blocked.
Moreover, the fact that the pores of the supporting element are
oriented substantially longitudinally with respect to the longitudinal axis of


CA 02778238 2012-04-19
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14
the outer sheath facilitates the regeneration of the biological tissue inside
said pores where the regeneration device is applied and, particularly for
applications related to the spinal cord, is designed to support the axial
growth of the axons and of the Schwann cell channels of the spinal cord.

Moreover, the fact that the mold of the supporting element is
constituted by a body having a substantially elongated shape along a preset
direction and forming an inner cavity with a transverse cross-section that is
shaped substantially like a semielliptical lobe defines the ideal geometric
shape that the supporting element must have.
Further, control of the immersion rate allows the development, along
the longitudinal axis of the supporting element, of a distinct thermal
gradient associated with the transport of heat and causes the crystals that
form by solidification of the aqueous suspension of collagen to have a shape
that is elongated in the heat transport direction that coincides with the
direction of immersion.
Moreover, the fact that the obtained supporting element undergoes a
stabilization step makes it possible to reduce the degradation rate of the
supporting element in vivo, increasing the density of the cross-linking
bonds that exist among the macromolecules of collagen. This bioabsorption
rate in vivo can be changed conveniently by varying the degree of cross-
linking of the polymer that constitutes the scaffold (i.e., the collagen).
These
variations of the degree of cross-linking can be performed by varying the
cross-linking technique (i.e., DHT, carbodiimide, formaldehyde) and/or the
time and temperature of the stabilization process.

Also, the fact that the supporting element undergoes a dry heat
sterilization step makes it possible to avoid damage and degradation of the
chemical and physical qualities of the supporting element.

Finally, the fact that the outer sheath and the supporting element are
provided with two independent processes makes it possible to have two
structures with mutually different characteristics and properties, and since


CA 02778238 2012-04-19
WO 2011/047970 PCT/EP2010/065048
only when the implantation occurs they are assembled together by insertion
of at least one supporting element in the outer sheath, makes it possible to
obtain a regeneration device that can be used for regenerating tissues
constituted by a plurality of parts with different requirements and
5 characteristics of regrowth.
Although the device according to the invention has been conceived in
particular to contain two supporting elements, it may be conceived to
contain a single supporting element or more than two supporting elements,
according to the requirements and the type of nerve on which the product
10 shall be applied.
Moreover, although the supporting element has been conceived as
having a substantially semielliptical transverse cross-section, it may
nonetheless have transverse cross-sections of another shape.

Finally, although the device according to the invention has been
15 conceived particularly for applications for regenerating the spinal cord,
it
may be used nonetheless, more generally, for regenerating peripheral
nerves, tendons, bones, cartilages, vessels and so forth.
The regeneration device and the corresponding manufacturing
method, thus conceived, are susceptible of numerous modifications and
variations, all of which are within the scope of the appended claims; all the
details may further be replaced with other technically equivalent elements.
In practice, the materials used, as well as the dimensions, may be any
according to requirements and to the state of the art.
The disclosures in Italian Patent Application No. MI2009A001804
from which this application claims priority are incorporated herein by
reference.
Where technical features mentioned in any claim are followed by
reference signs, those reference signs have been included for the sole
purpose of increasing the intelligibility of the claims and accordingly such
reference signs do not have any limiting effect on the interpretation of each


CA 02778238 2012-04-19
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16
element identified by way of example by such reference signs.

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date Unavailable
(86) PCT Filing Date 2010-10-07
(87) PCT Publication Date 2011-04-28
(85) National Entry 2012-04-19
Dead Application 2016-10-07

Abandonment History

Abandonment Date Reason Reinstatement Date
2013-10-07 FAILURE TO PAY APPLICATION MAINTENANCE FEE 2014-04-11
2014-10-07 FAILURE TO PAY APPLICATION MAINTENANCE FEE 2015-02-18
2015-10-07 FAILURE TO REQUEST EXAMINATION
2015-10-07 FAILURE TO PAY APPLICATION MAINTENANCE FEE

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Registration of a document - section 124 $100.00 2012-04-19
Application Fee $400.00 2012-04-19
Maintenance Fee - Application - New Act 2 2012-10-09 $100.00 2012-04-19
Reinstatement: Failure to Pay Application Maintenance Fees $200.00 2014-04-11
Maintenance Fee - Application - New Act 3 2013-10-07 $100.00 2014-04-11
Reinstatement: Failure to Pay Application Maintenance Fees $200.00 2015-02-18
Maintenance Fee - Application - New Act 4 2014-10-07 $100.00 2015-02-18
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
AS & PARTNERS S.R.L.
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Abstract 2012-04-19 2 61
Claims 2012-04-19 4 192
Drawings 2012-04-19 4 67
Description 2012-04-19 16 865
Representative Drawing 2012-04-19 1 4
Cover Page 2012-07-10 2 40
PCT 2012-04-19 11 411
Assignment 2012-04-19 7 193
Fees 2014-04-11 1 33
Fees 2015-02-18 1 33